Rheostat.



RHEOSTAT.

APPLIOATION ILED JAN. 10, i905.

I 2 SHEETS-SHEET 1.

FLA-L.. Ey

' www:

PATBNTED MAR. 27, 1906.

c. WIM. RHBQSTAT.

APPLIGTON FILED JAN. 10, 1905.

2 SHEETS-SHEET 2.

f l /l/ CHRLES lNlit'i, 0F GERB'IANTOWN,

PATENT ernten.

PENNSYLVANIA, ASSIGNOR T() PHE DELA i12/Muth).

RHEOSTAT Specification of Letters Potent.

' ratente March 27, 1908.

Application liled January 10.19.05. Serial No. 240,391.

To LH IIJ/mnt t 117,107/ coll/eerie.

Beit known that I, CHARLES Wm'r, e citizen ofthe United States, residing et Germantown, in the county of PhiladelphinA and Stets of Pennsylvanie, have invented e new and useful Rheosta-t, of which the following is n specification.

My invention relates to improvements in rheostets, my object being to provide an i mproved 'method of construction whereby a compnet i'ireprooi device may be made heving the least innnbcr of parts and being es free as possible trom liability to damage from overheating or the working loose of" mechanical astenings and electrical joints.

My invention especie-ll y comprises improved ineens for introducing e nen-conductive supporting mass within n resistance-coil to serve es :t form and sup ort therefor.

, My invention n so com prises various other details in construction :md assembling of the diilerent parts.

Referring to the drawings, Figure l is n ilan View ol'` my device with one-helll of the lmndle and top of the cnsing removed i"ig. 2 is nn elevation oi" my device with n que rtersection of the coil and 'elise removed on the lines es indiceted by b l) in Fig. l. Fig. 3.is e view of' the mandrel, showing method of windingr the coil. Fig', 4 is e plztn View oi n mold for introducing the supporting imiter-inl into` thee-oil, n portion of the top thereol' being;` broken :twaty to show the ends ol' the coil where the ,materiel enters. "Fig 5 .is n vertici l section on lines 5 5 of Figfft, the piston shown in elevation.

Similarnunicrnls reier to similnr parts throughout thc several views. l

ln Figs. l and 2 l show n rheostnt in which the resistnnecl is wound in n coil end the coil thcnbcnt into nn :tnnulnr shape. 'lhe switch 2 is mounted upon n centrally-positioned sh 'the outer pnrt oi seid switch 2 is preferably infiltrated, each brunch being composed ol' n. number of lmninael 25, thereby formingy brushes to-swecp the interior side of' the nunulor coil I, es isclenrly shown in Fig. 3. This switch 2 is clamped to the slntl't 3 by the nuts 'l, suitable insulntions, lsuch es mien \\':r;llers F3, being' interposed between seid nutsnmlswitcli. Uponshnl'tI-Sisnlsomounted the bundle It) lor the manuel operation ol" thc switch. l`hc terminal ring (i, which is electrically connectedwith one end oi the resistance-coil l, is connected with the bindingpost V7'. The other terminal ring 8 is electrically connected with the other cnd ol the resistance-coil l find is also connected with the binding-post t). rlhis` terminnl is ulso connected by :t llexible conductor l() with the switch 2. When the switch 2 is indirect contztet with terminal S, the entire resistnnce is in; but when the switch is rotated around to conteo-t with terminal ti the entire resistmice is cut out. Suitable stops (not shown) nre provided for limiting the two-wey movement of .seid switch 2-tln1t is, the switch moves in one direction es fnl'A es terminal (l end then in its movement in the other direction when it Venelles ternnnnl rlhe lormntion of the resistance clement is lhc split mnn'drel ll, ns shown in Fig'. 3'1s sccureil together by the screws l2 and then wound thereon. in the l'orm ol'` n long straight coil. lhis mnndrcl is shown es cylindricnl, but muy ol'` course bc ovnl, square, or olE other shnpc. It is divided `longitudilntlly on e plaine oblique to the axis, melting two wedgeshnped ports l'orconvcnicnce in withdrawing the nntndrcl zitter the coil is wound.

.'lh(` mlvontngc oi windingr the resistancecoil complete l'or e rheostnt with one piece of resistance in one operation is very obvious. it cll`ects :t `fren-.t savingr in cost. lNhen the straight cylindrical coil hns ,been removed l'rom thel mandrel, the terminal rings, such as 6 end 8, nrc secured to the ends thereof, eneh terminal ring electrically connected with one terminal ol` the resistentie-wire forming the coil. rlhc coil may then be formed into en ennulns :ind 'placed Ain the mold, (shown in Figs. 4 end 5,) this mold being split in two sections 13 :md 14, so that the same may be seperated to receive the coil, the coil 1 being vceretully fitted in one of the annuler channels .15 oi the mold, so that the two ends ofthe coil will approach toward the opening of the oondueting-.ehennel 16, leavin e space therebetween.- When the top helA 13 of the mold is iitted over the oeil end securely fastened to theother portion 14, n plastic .materiel-such es cement, plnster-oi-peris, or the like-is fed into the top of cylinderl? end forced downwardly by piston 18, through channel 16, into annuler chunnel l5, in end about the encounters e stOP., While it is simile rly limited extremely simple und convenient, as follows@ mounten in the lnt'hc-centcrs and the wire IOO convolutions of coill 1, and filling the entire s ace therewith. This plastic material s iould have the property of hardening or of being hardened by some suitable method. Then the same has become thoroufrhly hardened, the coil may be removed rom the mold. 'Ihe said coil 1 and its core now form a lirm, compact, and self-supporting body, with the two ends of the resistance-coil electrically connected with terminal rings 6 and 8. A box 2() is now provided, such as is shown in Figs. l and 2, around the interior of which is placed a ringr 21, of insulating material, such as mica. Upon the top is also placed. the mica disk 22. The resistance-ring then being inserted in the case, another mica disk 23 is' laid upon it, and the base 24 is forced into place and secured by screws. 'lhe ,rounding parts.

resistance clement is thus securely held in place and eilieiently insulated from the sur- It is understood, of course, that prior to the placing of thebase 24 in position the switch 2 has also been placed in position7 one o'f the significant features of this construction beiner that by a simple 'fitting or proper dimensioning ol' the various partsthe resistance ma)v he secured in place with respect to tl i associated mechanism simply in the manner above described without anything further than the mere insertion of the binding-post screws 7 and 9 through the casing 2() into the two terminal rings 6 and 8.

W'hile l have shown the coil in the form of a helix, it is obvious that this coil may have any other cross-section, and instead of being bent into an annular' shape it may be perfectly straight or in other form Without departing from the spirit of my invention.

What I claim is-` 1. In a rheostat, a removable resistance element composed of a helical coil of Wire bent into a circular Jform and having a core of plastic material Which has the propertyof becoming hard.

2. ln a rheostat, a removable resistance clement composed of a helical coil of Wire bent into a circular form and having a core of plastic material which has the property of becoming hard, and terminals in electrical connection therewith. r

3. In a rheostat, the combination of a casing, a removable resistance element cornposed of' a helical coil of Wire bent into a circular form and having a core of plastic material, which has the property or becoming hard, and a manually-operated Switch adapted to sweep the inner periphery of said resistance element.

4. In a rheostat, the combination of a cas-' ing, a removable resistance element adapted to iit said casing and composed of a helical coil of wire bent into a circular form and having a core `of plastic material Which has the property of becoming hard terminals secured to said resistance element and bindingpostsprojecting through the casing into said terminals. u (`IIARLES l/VIRT.

Witnesses:

CHAs. C. TRUMP, HOWARD S. OKIE. 

